Question

Select the incorrect statement about $N _{2} F _{4}$ and $N _{2} H _{4}$ :
(I) In $N _{2} F _{4},$ $d-$ orbitals are contracted by electronegative fluorine atoms, but $d-$ orbital contraction is not possible by $H-$ atom in $N _{2} H _{4}$
(II) The $N - N$ bond energy in $N _{2} F _{4}$ is more than $N - N$ bond energy in $N _{2} H _{4}$
(III) The $N - N$ bond length in $N _{2} F _{4}$ is more than that in $N _{2} H _{4}$
(IV) The $N - N$ bond length in $N _{2} F _{4}$ is less than that in $N _{2} H _{4}$
Choose the correct code-

• A. I, II and III
• B. I and III
• C. II and IV
• D. II and III

Answer 1

Answer: (B)

In $N _{2} F _{4}, N - N$ bond has more s-character hence bond length decreases.

While in $N _{2} H _{4}, N - N$ bond has less s-character (i.e., more p-character), hence bond lengths is more.